13. The secretary of the WLTP informal subgroup on the Development of the Harmonized driving Cycle (DHC) introduced GRPE-66-34, containing the report on the progress made since January 2013. Having stated that almost all open issues were successfully closed, he reported that DHC successfully developed the harmonized test cycles, including the downscale procedure (even if the downscale calculation formula requires finalization after correcting minor issues), the mode construction, and the gear shift prescription (notwithstanding continued work for its improvement). A draft final report on the development of the Worldwide harmonized Light vehicles Test Cycle (WLTC) is already available and will be included in the Technical Report.

15. The Chair of the informal subgroup on the Development of the Test Procedure (DTP) reported on the work status of the subgroup (GRPE-66-36). He stated that there are a number of remaining open issues that need to be addressed. According to the mandate documents (ECE/TRANS/WP.29/AC.3/26 and Add.1) three phases are included in the WLTP terms of reference: phase I, concerning the development of the UN GTR (test cycle and test procedure); phase II, concerning on-board diagnostics (OBD) and additional tests (e.g. on pollutants other than CO, NOX, hydrocarbons and particulate matter); and phase III, about reference fuels and performance requirements. Phase I can be further divided in two stages, with the aim to continue work on still open issues and to improve and correct the text of the GTR based on validation and experience. The issues that are foreseen to be solved in phase I, stage 1, include: (i) Rechargeable electric energy storage system Charge Balance (RCB) correction; (ii) the warm-up procedure for the road load and dynamometer setting; (iii) the speed trace violation, concerning deviations from the test cycle beyond the prescribed tolerances; (iv) the definition of the predominant mode for vehicles with multimode gearboxes; and (v) the temperature correction for regional representative conditions for the CO2 emission determination. Other issues could be finalized in phase I, stage 1, or eventually (in a fall back solution) postponed to stage 2: (i) the table of running resistances, concerning default values to be used in the dynamometer settings if the road load cannot be determined; (ii) the ambient temperature for coast-down (the latest discussions were settling on 5 to 40°C ± 5°C); and (iii) utility factors on electric vehicles. If an agreement is not reached in phase 1, stage 1, the issues will need to be defined regionally. Concluding his intervention of the status of the DTP subgroup, the DTP Chair reported that, even if the coast down and wheel torque methods are agreed, the wind tunnel and the comparison of road load determination methods are likely to be addressed in phase I, stage 2.